Mine stopping panels are used to control the flow of air through mine passages. Mine stopping panels of the type sold by Kennedy Metal Products & Buildings, Inc. are described in U.S. Pat. Nos. 4,483,642, 4,695,035, 4,820,081, and 7,267,505, all of which are incorporated by reference herein. These panels generally comprise first and second sheet metal panel members having a telescoping sliding fit one inside the other, and channel-shaped end caps attached to the panel members at opposite ends of the panel. The panel members are extended to bring seals in the end caps into sealing engagement with the floor and roof of a mine passage. The attachment of the end caps to respective panel members has been achieved in different ways.
One method of attachment was a simple draw-displacement connection in which a punch punches a hole through two sheets (one sheet of the panel member and another sheet of the end cap), shearing on two opposite sides and stretching the other two. The punch goes through both sheets and coins (displaces) the material pushed through against an anvil to make it quite a bit bigger than the slot from which it came. Another method was basic resistance (spot) welding. Still another method involved punching a small hole that was sheared on three sides through both sheets, and then folding the resulting tab back against the bottom of the bottom sheet. Another method was similar to a desk stapler. Very hard wire was forced through the sheets and folded against the bottom sheet. All of these methods have various drawbacks.
There is a need, therefore, for an improved mechanism for attaching the ends caps to respective panel members.